How to estimate aortic characteristic impedance from magnetic resonance and applanation tonometry data?

2015 ◽  
Vol 33 (3) ◽  
pp. 575-583 ◽  
Author(s):  
Emilie Bollache ◽  
Nadjia Kachenoura ◽  
Ioannis Bargiotas ◽  
Alain Giron ◽  
Alain De Cesare ◽  
...  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pauliina Kangas ◽  
Antti Tikkakoski ◽  
Jarkko Kettunen ◽  
Arttu Eräranta ◽  
Heini Huhtala ◽  
...  

AbstractThe increase in cardiovascular risk associated with metabolic syndrome (MS) seems higher in women than in men. We examined hemodynamics during head-up tilt in 252 men and 250 women without atherosclerosis, diabetes, or antihypertensive medication, mean age 48 years, using whole-body impedance cardiography and radial pulse wave analysis. MS was defined according to Alberti et al. 2009. Men and women with MS presented with corresponding elevations of systolic and diastolic blood pressure (10-14%, p ≤ 0.001) versus controls. Supine pulse wave velocity (16–17%, p < 0.001) and systemic vascular resistance (7–9%, p ≤ 0.026), and upright cardiac output (6–11%, p ≤ 0.008) were higher in both MS groups than controls. Elevation of supine aortic characteristic impedance was higher in women than in men with MS (16% vs. 8%, p = 0.026), and in contrast to men, no upright impedance reduction was observed in women. When upright, women but not men with MS showed faster return of reflected pressure wave (p = 0.036), and smaller decrease in left cardiac work (p = 0.035) versus controls. The faster upright return of reflected pressure, lower upright decrease in left cardiac work, and higher elevation of aortic characteristic impedance may contribute to the greater increase in MS-related cardiovascular risk in women than in men.


Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Sara L Hungerford ◽  
Audrey Adji ◽  
Nicole K Bart ◽  
Linda Lin ◽  
Andrew Jabbour ◽  
...  

Introduction: Valvuloarterial impedance (Z VA ) represents the valvular and arterial factors that oppose Left Ventricular (LV) ejection and is recognised as an important index to assess global LV load in patients with Aortic Stenosis (AS). Z VA is traditionally determined by Transthoracic Echocardiogram (TTE) and brachial cuff pressure. Hypothesis: Our study sought to compare Z VA-TTE with Z VA calculated using a simultaneous Cardiac Magnetic Resonance (CMR) and Applanation Tonometry (AT) (Z VA-CMR ) technique to determine whether TTE measurement of aortic flow velocity resulted in an underestimation of Z VA. Methods: Twenty AS patients underwent a protocol of CMR/AT followed by TTE. Z VA-CMR was determined as the relationship of derived aortic pressure (radial) to CMR aortic flow velocity in the frequency domain. Z VA-TTE was determined from digitised flow velocity within the left ventricular outflow tract (LVOT) on pulsed-wave Doppler and derived central pressure waveforms. Systemic vascular resistance (SVR) was calculated from mean pressure and flow. Values from both methods were compared. Results: Our study found that Z VA-TTE values (mean±SD, 638±381 dyne.s.cm -3 ) were consistently lower (p=0.07) than Z VA-CMR values (946±318 dyne.s.cm -3 ), and attribute this to an overestimation of LVOT flow velocity on TTE. SVR calculated by CMR/AT (2215±616 dyne.s.cm -5 ) was almost four times higher than TTE (618±245 dyne.s.cm -5 ) (p<0.001). This is due to more robust axi-symmetrical sampling of aortic flow across the entire cross-section of the ascending aorta (well above the stenotic jet) during CMR, than using operator-dependent TTE. Conclusions: Whilst Z VA -TTE is commonly performed in patients with AS to assess global LV load, newer methods to assess Z VA using simultaneous CMR/AT likely represent a more accurate non-invasive assessment.


2016 ◽  
Vol 34 (6) ◽  
pp. 1099-1108 ◽  
Author(s):  
Audrey Adji ◽  
Nadjia Kachenoura ◽  
Emilie Bollache ◽  
Alberto P. Avolio ◽  
Michael F. O’Rourke ◽  
...  

Hypertension ◽  
2020 ◽  
Vol 75 (5) ◽  
pp. 1260-1270
Author(s):  
Keneilwe N. Mmopi ◽  
Gavin R. Norton ◽  
Hamza Bello ◽  
Carlos Libhaber ◽  
Mohlabani Masiu ◽  
...  

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